Just to be clear: I am not a doctor. Use your brain before following my advice and consult a doctor. Don't kill yourself.
Having said that, the following practices are pretty safe and unlikely to kill you. None of the what follows is original research. I am just synthesizing what master researchers tell and I felt that their message was important enough to repeat. Some of the people I use as references are Tim Ferriss, Ray Cronise, Wim Hof
I am going to tell some facts about things you may already know - how to do it, benefits, and common myths.
But before I do that, here's a philosophy that I have developed after much stress and testing.